Solving Water Intrusion into VERY SHORT Dirt Crawlspace

Though this isn't the crawlspace, it's shows what kind of water problems we were facing.
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To give a bit of context, the dirt crawlspace under my house is literally a crawlspace. There is no squatting in the space. I literally have to crawl to move from one end of the house to the other. And its a dirt crawlspace, so I always get very muddy.

During the winter months when it starts to rain, I made a simple observation that there was water pooling that covered around 60% of the grass in my fairly small backyard. Being a bit naive about maintaining a home, I checked under the house after being advised to and found there was probably at least one inch of water covering as far as I could see under the house!

Since the house sits on concrete, I figured it wasn't a bad thing for the short term, but after reading up online found that water in the crawlspace isn't good for many reasons:

  • Water can cause moisture which then can rot wood (even if not in direct contact).
  • Moisture content can be worse (more evaporation) if the heater vents under the house is running and leaks warm air.
  • Water can be an invitation for animals to nest, especially in the cold of winter. Wild animals can bring along disease as well.

After more online research, I found three common problems that could be the source of water in the crawlspace. I did what I could for each problem to eliminate it as a source.

  1. Space around the house should be downward sloped away from the foundation.
  2. Gutters should not be overflowing and water from downspouts should be directed away from the foundation.
  3. Check for natural springs (though this is much less common) under the house.

Gutters and Downspouts

The easiest to visual check and resolve during the winter when it was still raining is to visually verify the gutters weren't overflowing. A quick look during heavy rain under an umbrella confirmed this around the house.

Next, it turns all almost all the downspouts (four of them) were just draining right at the foundation!

  • The 2 downspouts in the front of the house had drains to the street, but were missing the 90 degree turn to force the water down the spout. A simple purchase of a flexible angled drain pipe adapter solved that problem. Before you purchase, you'll need visible check the shape and measure dimensions of both the ends to make sure it fits. Due to the nature of the tight spacing, I had to creatively cut part of the pipe adapter to fit it together. Now 100% of the water from the two downspouts at the front of the house drain completely to the street!
  • The 2 downspouts in the back of the house drained to the foundation. It looked like the previous owners knew there was an issue, as upon further inspection and light digging showed there were a couple of bricks where the water hit the ground. The solution for these were trickier, as the right solution would be to dig and (or hire contractors to) install a french drain to drain both back to the street. That would likely cause $1000s of the dollars in our region. My cheaper solution was to use flexible/expandable landscaping pipes to drain rainwater to the street during the rainy winter month (when I'm not in the backyard anyways). I stash them on the sideyard in the summer when I'm entertaining in the backyard.

All these fixes to resolve the four downspouts costed around $100, which is a small price to pay to resolve water in crawlspace issues. Unfortunately, this did not solve the problem.

Downward Slope Space Around House

Being the middle of winter, there wasn't much I could do to re-level the slope of the grass. I had a hunch there was an issue with the slope, since water was pooling. But wasn't 100% certain since I never saw water actually flowing towards the house. Being that that our region was under several years of drought, I figured instead of correcting the slope and putting in new grass, I would have contractors install paver stones, which look better than concrete squares.

This project was much more expensive and I wasn't sure it would solve the issue, since the pavers only covered the backyard, and none of the sideyard which could theoretically also be causing problems. Surprisingly, after the installation (which took longer than it expected... we didn't finish before the next years rain arrived), the paver stones solved the problem! The space under the crawlspace stopped pooling up with water!

Sump Pump Solution

This is my least favorite solution, but the goal here was to dig a pit where you drop a pump which would then drain out the water. The concept here is that water is flows via the least resistance, in the case a hole. The problem is its less effective in an areas with heavy clay (because it is more dense). I suspected my area was full of clay. To find out if a sump pump was a solution, I spent several weekends digging a hole with a shovel during the winter months. Also to my surprise, there was water in the hole I dug. So I went ahead and purchased what I would need to finish the installation:

  • Sump Pump - I picked one that was too powerful for my needs (too many gallons drained per minute) which would have caused the pump to prematurely burn out. Also remember you'll need a power source.
  • Sump Basin - To keep out dirt and a clear place to put the pump to drain out. Be prepared to dig a hole 2 inches deeper than the sump basin is tall.
  • Gravel - to prevent dirt from entering the sump basin.

However, since I ended completing the paver project (which was the solution to standing water in crawlspace), I never finished this installation. In my opinion, this is better because having a sump pump solution requires both power and occasional maintenance.

Other Resources:

Ever since we moved into our home in Millbrae, our guests have commented our home is notably chilly. We felt it too, but wasn't sure what to do about it. Here's are the projects I've done to improve the temperatures inside my home. For those not familiar with Millbrae, it is a city in the SF Bay Area. The weather rarely gets to freezing temperatures in the winter and rarely gets to 100F in the summer. We never get snow.
  1. Results of Re-Insulating Attic in SF Bay Area
  2. How to Seal Power Outlets and Switch Airleaks
  3. Better Home Insulation by Sealing Gaps
  4. My Dog Door for Sliding Patio Door Is Drafty? Seal it with Insulation!
  5. Solving Water Intrusion into VERY SHORT Dirt Crawlspace
  6. Alternative to Messy "Great Stuff"
  7. How to air seal recessed lights on a budget?
  8. My Research on Vapor Barriers Before Meeting a Crawlspace Contractor
  9. How to Stop Cold Air from a Unused Fireplace
  10. Stop Draft around Gap of a Unevenly Warped Front Door
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